Lightning is essentially a giant spark of electricity, created by the thunderstorm process. Thunderstorms form when significant condensation, resulting in the production of a wide range of water droplets and ice crystals, occurs in an atmosphere that is unstable and supports deep, rapid upward motion. This often occurs in the presence of three conditions: sufficient moisture accumulated in the lower atmosphere, reflected by high dewpoint temperatures; a significant fall in air temperature with increasing height, known as a steep lapse rate; and a force such as mechanical convergence along a cold front that will focus the lift.
When these weather factors come together and initiate a thunderstorm, the thunderstorm cloud develops charge in the cloud. Typically, positive charge builds at the top of the cloud and negative charge at the bottom of the cloud early in the thunderstorm lifecycle. (Think of a standard Duracell battery – charges at opposite ends). A stepped leader of charge leaves the cloud and rapidly travels towards the earth’s surface following the least path of resistance. This first stepped leader stroke approaches ground in discrete steps of about 100 to 150 feet or more. This channel is usually not visible to the human eye until it connects with the earth’s surface (opposite charge) and the circuit completes and the electricity flows (the lightning strikes). Charge can travel through this ionized channel one or multiple times. Each independent pulse of electricity is called a stroke. Multiple strokes through the same channel are grouped as a flash.
Thunder is the audible result of the massive and extremely rapid heating of the channel of air in which the lightning has traveled. The result is an explosion of the air. Lightning strikes and then thunder follows. Depending on your proximity to the lightning ground strike point, these may occur simultaneously (if you are very nearby) or up to many seconds later (further away) given that the speed of light travels faster than the speed of sound.
The United States Precision Lightning Network (USPLN) is a network of ground-based time of arrival sensors that detect the electric wave form given off by a lightning event.
Lightning has a unique wave form that is discriminated from all other electric wave forms (noise) to determine that a lightning event has occurred. As the wave form travels over the earth’s surface, each sensor uses a highly accurate GPS (global positioning system) clock to time-stamp the event. The individual sensor data is instantaneous sent to our central analyzers for correlation with other sensors to determine where the stroke of lightning occurred. While only three sensors are required to detect the lightning strike and produce an accurate ground strike location, the majority of lightning events are detected by 20+ sensors.
Typical USPLN installation.
Lightning detector on the left, GPS clock on the right.
Our state-of-the-art control center and network hub is located in Melbourne, Florida. A fully redundant control center operates in tandem in Oklahoma City, Oklahoma. Constant self-monitoring performance technology exists within each sensor, all communication methods are monitored in real-time and the network hub performance is also continuously examined through automated procedures.
LightningTrax™ is an address and date(s) specific verification of the occurrence of lightning on the earth’s surface. LightningTrax™ reports make use of the precision performance of the USPLN to accurately validate the presence or absence of cloud-to-ground lightning strikes.
LightningTrax™ reports and LightningExpress™ Service are 95% accurate in reporting the presence (one or more strokes detected within a 1 mile radius) or absence (zero strikes detected within a 5 mile radius) of lightning.
A basic LightningTrax™ reports sells for $95 and includes the written report for up to a 72 hour search period, a print-out of lightning strike data and a full color map. Please see our Pricing page for full details.
LightningTrax™ reports are purchased on-line. Upon submitting your request, the USPLN database is accessed and the report created “while you wait”. Most reports are available with 1 minute of your request and the reports can be downloaded and/or stored on-line in your password protected account.
USPLN offers either account privileges with terms of Net30 for approved repeat customers and credit card payment for occasional customers. Customers paying by credit card must enter their credit card number on each purchase, as credit card information is not stored on our servers. Pre-payment by check or money order is also accepted.
Both products are available for any location/address within the contiguous United States.
The USPLN archive data are available from 05-01-05 forward. If you need verification of a date prior to this time, please contact us at 888.255.7099.
The precision accuracy of the USPLN allows for affirmative confirmation of the presence of lightning by searching a one mile search radius around a specific latitude/longitude coordinate (address). Because lightning can strike nearby and induce a surge over a large area, the USPLN first checks for direct strikes by searching a one (1) mile radius and if no lightning is found, the radius is auto-enlarged to a five mile search radius to detect any nearby lightning that could have impacted the address of interest. This provides the most accurate lightning reports possible.
Lightning and thunder can be seen and heard from significant distances, depending on visual and audible attenuation factors (humidity, cloud cover, ground clutter [trees, buildings, etc]). The property owner may have observed distant lightning or a variety of cloud lightning (lightning that does not come in contact with the earth’s surface) overhead. We also suggest double checking your facts as to the date of the search and the address of the property in question.
We stand behind every report we produce. If you need technical expertise to assist in a court case, please contact us at 888.255.7099 or info@weatherforensics.com
for phone consultation, deposition and court appearances.
Yes, WDT has two Certified Consulting Meteorologists on staff plus other highly trained meteorologists and lightning experts to assist you. Hourly fees quoted upon request.
USPLN lightning stroke detection occurs through the scientific measurement and precise location plotting on the earth’s surface. Most times, lightning reports from different lightning networks will be highly similar; however, any given lightning strike may be measured slightly differently. An “apples-to-apples” comparison would be to compare the binary results (presence or absence of lightning) of a given lightning report from each network. While the USPLN is the newest and most state-of-art lightning detection network, customers of lightning verification reports should not make the assumption that the USPLN output is ground truth and the other network is “inaccurate” – and vice versa.
For verification of 100+ claims per year, we recommend our LightningExpress™ Service. LightningExpress™ allows direct access to the USPLN database of lightning strikes, all for one set annual fee.
